EXPERIMENT OF PUMPING AT CONSTANT-HEAD: AN ALTERNATIVE POSSIBILITY TO THE SUSTAINABLE YIELD OF A WELL

Abstract

The effects of constant-head pumping on a well over a period of 1 year have been monitored and the results used in the research of a potential alternative for the attainment of sustainable yield. Sustainable yield is frequently related to the response of drawdown during a pumping test at constant-rate, which sometimes involves a difficult choice of conceptual model to be used to analyse the pumping results. The experiment, carried out on a well that taps a fractured aquifer in Italy, recorded the aquifer's response to pumping, compared with the response of springs. From the trends in discharge variation with time, the period and magnitude of the recharge and the stored water volume at the beginning of the depletion period can be evaluated, and the discharge rate during the same depletion period can be predicted. A sustainable yield can be derived based on the water volume extracted during the depletion period rather than on the prediction of drawdown over a long time. The experiment also highlights the stability of water quality extracted from the well, and where this criterion is important, in some cases, the constant-head pumping can represent an alternative method of groundwater exploitation.